Piston expander



Oct. 5, 1937. DIENNIE 2,095,029

- PISTON EXPANDER Filed Feb. 24, 1936 fig 1 z Z0 INVENTOR l d EDWARD ,6. DEN/VIE A TTORNEY Patented Oct. 5, 1937 UNITED STATES PATENT OFFICE;

PISTON EXPANDER Edward B. Dennie, Hollywood, Calif.

Application February'24, 1936, Serial No. 65,343

6 Claims.

This invention relates to anaccessory for engines, and particularly pertains to a piston ex pander.

In various types of engines, especially internal combustion engines, it has become common practice to form the engine pistons of light weight material, and to form a longitudinal slit in the skirt of the piston so that expansion and contraction of the piston may take place without undue binding or wear between the piston and its cylinder. however, wear gradually occurs on the outer cylindrical surface of the piston until the piston is loosened within the cylinder and does not fit with the proper tightness. Various devices have been designed to expand the split skirtof the piston so that there will be a proper tight fit between the skirt of the piston and its cylinder. Some of these devices have been in the form of expand ing elements having prongs attached to a yielding member, the resilience of which acts to expand the piston at opposite sides of the slit in the piston skirt. Such structures are applied by drilling holes through the skirt of the piston. An example of a device of this character is shown in a patent issued to Charles M. ON'eil, dated March 22, 1932, No. 1,850,214. In a structure of the type shown in the aforesaid patent the expansive action is dependent solely upon the inherent resiliency of the spring of which it is made. There is no way to vary the effectiveness of such an expanding element and no way to maintain it in an adjusted position. It is also desirable to provide a device which will operate without binding and without excessive wear between its various elements. It is the principal object of the present invention, therefore, to provide a piston expanding device which does not depend upon the resilience of the expanding element for its action, but which is fitted with mechanical adjusting means for directly expanding and holdingthe piston in its set position and which operatesfreely with minimum wear.

The present invention contemplates the provision of a ring-shaped member having lugs upon diametrically opposite sides thereof adapted to seat within openings drilled in the skirt of the piston, the structure being further provided with means whereby positive adjustable separation of the lugs may be obtained at all times.

The invention is illustrated by way of example in the accompanying drawing in which:

Figure 1 is a view in central longitudinal section through a piston having a split skirt and During the use of pistons of this type,

showing the application of the present invention thereto.

Fig. 2 is aview in longitudinal section through the piston as seen on the line 22 of Fig. 1-,"further disclosing the manner in which the expander is applied. j

Fig. 3 is an enlarged view in transversesection showing the exact construction and application of the expander to the piston.

Fig. 4 is an enlarged view in perspective showing the piston expanding device. 7

Fig. 5 is a view in perspective showing another form of the expanding element. V

Fig. 6is an enlarged viewsho-wing the relationship of one of the prongs to an opening in the piston skirt as seen on the line 6-6 of Fig. 3.

Fig. 7 is an enlarged fragmentary View showing the relation of the clamping nut to the expanding ring. 7

Fig. 8 is a view showing the blank from which the expander is formed. 7

Referring more particularly to the drawing, l0 indicates an engine piston having a head II and a cylinder skirt l2. This skirt is split longitudinally as indicated at l3, the upper end of the split terminating in a transverse split l4; sired to expand the skirt at the split in order' to take up wear. In the present instance this is accomplished by a piston expanding device indicated in perspective in Fig. 4 of the drawing and designated by the numeral l5. This device is shown as applied tothe piston skirt in Fig. 1 of the drawing where it will be seen that it spans the split l3, and is fitted with prongs I 6 which protrude into openings l8 formed through the skirt of the piston at opposite sides of the slit l3. The prongs, as shown particularly in Figs. 4 and 8 of the drawing, project from one side of a ringshaped body member 20. The prongs I6 are struck as part of the blank from which the ringshaped member 20 is formed and protrude from one side thereof as shown in Fig. 8 of the drawing. These prongs are arcuate in cross-section and are struck on the same radius as that of the openings it into which they extend as shown in Fig. 6 of the drawing. Attention is directed to the fact that normally the prongs assume a position above center of a line passing through the centers of both openings 18. This makes it possible for the prongs to slide'along and around the face of 'the'openings when the piston is expanded or when it contracts. There is always, therefore, an appreciable surface contact between the outer face of the prongs I6 and the faces of the openings l8. This prevents excessive wear and also It is de- These end portionsbear against inclined faces other in an easy sliding movement, With reference to Fig. 3 of the drawing, it will be seen that the openings I3 are formed at their outer ends with tapered,

countersunk portions outer ends of the prongs I6 flare outwardly as in-- dicated at IT to hook into the counterbore and hold the structure in position. The body member is substantially circular in shape'when finished and is preferably formed of a piece'of flat steel.

from one side of which the prongs l6 are struck. When finished, the terminating ends of the strip of flat steelare inturned as indicated at 2| and 22 and fit within a. channel groove formed at opposite sides of an expansion block 23. This block may be solid as shown in Fig. 4, or may be struck,

from a single piece of strip material, as indicated in Fig. 5. In any event, channels 24 will occur at opposite sides of the block and will-receive'the inturned end portions 2| and 22 of the ring 2|).

of the expanding member 23 so that, as the mem .ber 23 is drawn downwardly and-between the inturned ends 2| and 22 of-"the ring .20, the ring will be adjustably expanded by the wedge action. A screw 26 extends through the expanding block; and carries a cross member or nut 21 at its inner.

end. This cross member seats within a recessed edge 28 of the inturned ends 2| and 22 'sothat the blockwill be drawn into a wedging position between the members 2| and 22 to produce'accurat adjustment of the expander. i v

Attention is directed to Fig. 7 of the drawing, Where it will be seen that the upper face of the nut 21 is tapered. This taper is required to conform to the faces of recesses 28, that have previously been cut into the flat blank, and when the members 2| and 22 have been bent inwardly and radially of the member 20, the wall faces of the recesses will assume a full sliding contact with the inclined faces of the nut 21. r In the operation of the present invention, the expanding structure |5 may be assembled as shown in the drawing, and the skirt of the piston may be prepared by drilling the holes l8 and I9 therein, as shown in Fig. 1 of the drawing, after which the prongs l6 and I1 may be fitted into the holes |8 and IS. .The head of the screw 26 is faced downwardly toward the opened end of the skirt and by adjusting the screw any desired amount of expansion may be created as the explied to a piston, and that after it has been applied it may be instantly adjusted to create a .de-'

sired amount of expansion for the skirt of the piston and the necessary fit between the piston and its cylinder. Furthermore, it will be seen that at every point-of sliding contact the possibility of binding, friction and wear has been reduced to the minimum. 7 7

While I have shown the preferred form of my invention, as now known to me, it will be understood that various changes might be made in the combination, construction and arrangement of parts, by those skilled in the art, without departing from the spirit of the invention as claimed.

Having thus described my invention, what I claini'and desire to secure by Letters Patent is:

H. The

' opposite sides of its split.

said skirt being provided with a slit to permit ex- I pansion thereof and having openings on both V 1 sides of said split, an expansion device comprising a split annular member lying in a plane parallel to the skirt and havinga pair of prongsadapted to seat within the openings of the skirt at oppoly engaging the piston at oposite sides of its split,

and means adjustably interposedbetween the free 7 ends of the split annulus to adjust the positions of the prongs with relation to each other.

3. In combination withthe split skirt of a piston, said skirt being formed with a pairof openings therethrough, one on each side of thesplit; in the skirt, a piston expander comprising an annular member; formed'from a strip of flat metal. whereby said member will be yieldable 'circum-J- ferentiallybut substantially rigid laterally, .said

cumference, abutments formed at said split ends of the annular member and inclined with relation to each other, an adjustable block interposed be-.; tween said abutments and having inclined faces,

means for adjustably setting said block between said inclined abutments, and a pair of prongs ex tending from oneside of the annular member and adapted to positively. engage the piston skirt at 4. In a piston expander of the type described, an annular expanding'ring formed of a continuous strip of metal, the opposite ends of which are bent inwardly along radial lines of said ring and I annular member beingsplit at a point in its cirare spaced from each other to form an angular V throat, a wedge element having inclined faces agreeing with the faces of said inturned members,

a screw passing through the center of said wedge element and a nut carried at the lower end thereof formed with faces inclined to bear against the end faces of the inturned portion of the rings.

5. In combination with a piston having a skirt provided with a split to permit expansion thereof, an expanding member comprising a split annulus, a pair of prongs formed at opposite sides of the annular member positively engaging thepiston skirt upon opposite sides of said split, a

wedge block interposed within the split of the annulus whereby adjustment of the wedge block will increase or decrease the lateral tension upon ence, an adjustable wedge block disposed within:

said split, a pair of prongs carried by said annu- I lar. expanding member and adapted to positively engage the piston. skirt at opposite sides of the split and adjusting means associated with the wedge block whereby the tension exerted upon the piston skirt by the prongs may be selectively increased or decreased.

EDWARD B. DENNIE. 

